Buildresult: powerpc-fixes/mmu_defconfig/microblaze-gcc5 built on May 4 2020, 13:57

kisskb

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Status:	OK
Date/Time:	May 4 2020, 13:57
Duration:	0:01:48.069447
Builder:	ka1
Revision:	powerpc/64s: Fix unrecoverable SLB crashes due to preemption check (`3fa6fc04815a70a110445368c8741c178970c87d)`
Target:	powerpc-fixes/mmu_defconfig/microblaze-gcc5
Branch:	powerpc-fixes
Compiler:	microblaze-gcc5 (microblazeel-linux-gcc.br_real (Buildroot 2016.11-git-00613-ge98b4dd) 5.4.0 / GNU ld (GNU Binutils) 2.26.1)
Config:	mmu_defconfig (download)
Log:	Download original Possible warnings (1) kernel/futex.c:1676:17: warning: 'oldval' may be used uninitialized in this function [-Wmaybe-uninitialized] Full Log # git rev-parse -q --verify 3fa6fc04815a70a110445368c8741c178970c87d^{commit} 3fa6fc04815a70a110445368c8741c178970c87d already have revision, skipping fetch # git checkout -q -f -B kisskb 3fa6fc04815a70a110445368c8741c178970c87d # git clean -qxdf # < git log -1 # commit 3fa6fc04815a70a110445368c8741c178970c87d # Author: Michael Ellerman <mpe@ellerman.id.au> # Date: Sun May 3 00:33:16 2020 +1000 # # powerpc/64s: Fix unrecoverable SLB crashes due to preemption check # # Hugh reported that his trusty G5 crashed after a few hours under load # with an "Unrecoverable exception 380". # # The crash is in interrupt_return() where we check lazy_irq_pending(), # which calls get_paca() and with CONFIG_DEBUG_PREEMPT=y that goes to # check_preemption_disabled() via debug_smp_processor_id(). # # As Nick explained on the list: # # Problem is MSR[RI] is cleared here, ready to do the last few things # for interrupt return where we're not allowed to take any other # interrupts. # # SLB interrupts can happen just about anywhere aside from kernel # text, global variables, and stack. When that hits, it appears to be # unrecoverable due to RI=0. # # The problematic access is in preempt_count() which is: # # return READ_ONCE(current_thread_info()->preempt_count); # # Because of THREAD_INFO_IN_TASK, current_thread_info() just points to # current, so the access is to somewhere in kernel memory, but not on # the stack or in .data, which means it can cause an SLB miss. If we # take an SLB miss with RI=0 it is fatal. # # The easiest solution is to add a version of lazy_irq_pending() that # doesn't do the preemption check and call it from the interrupt return # path. # # Fixes: 68b34588e202 ("powerpc/64/sycall: Implement syscall entry/exit logic in C") # Reported-by: Hugh Dickins <hughd@google.com> # Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> # Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> # Link: https://lore.kernel.org/r/20200502143316.929341-1-mpe@ellerman.id.au # < /opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-gcc --version # < /opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-ld --version # < git log --format=%s --max-count=1 3fa6fc04815a70a110445368c8741c178970c87d # < make -s -j 8 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux- mmu_defconfig # < make -s -j 8 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux- help # make -s -j 8 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux- olddefconfig # make -s -j 8 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux- /kisskb/src/scripts/Makefile.asm-generic:25: redundant generic-y found in arch/microblaze/include/asm/Kbuild: hw_irq.h /kisskb/src/kernel/futex.c: In function 'do_futex': /kisskb/src/kernel/futex.c:1676:17: warning: 'oldval' may be used uninitialized in this function [-Wmaybe-uninitialized] return oldval == cmparg; ^ /kisskb/src/kernel/futex.c:1652:6: note: 'oldval' was declared here int oldval, ret; ^ Kernel: arch/microblaze/boot/linux.bin is ready (#1) Completed OK # rm -rf /kisskb/build/powerpc-fixes_mmu_defconfig_microblaze # Build took: 0:01:48.069447

© Michael Ellerman 2006-2018.